The invention relates to a mechanical automatic winding device or spring winding device for the driving spring or watch spring of a mechanical clockwork of a wristwatch (automatic winding watch) and to a wristwatch with such a winding device.
Wristwatches with a mechanical clockwork and with an automatic winding device that winds the driving spring or watch spring when the wristwatch is moved are known in the art. The winding device in such watches generally consists of an unbalanced mass or eccentric mass that is located on the back of the clockwork and can be swiveled on a central clockwork axis, the swivel motion being converted by a gear array into a rotary motion that winds the clockwork spring.
A disadvantage of such mechanical automatic winding watches is that the shaft forming the swivel joint for the eccentric mass also serves to support this mass. In the event of jolts, vibrations or similar shock loads to the wristwatch, the forces occurring on the eccentric mass have to be absorbed by this shaft, which can easily result in damage to the watch.
Also known is the use of balls as the eccentric mass in mechanical winding devices for wristwatches, the balls being provided in a circular ball guide enclosing the clockwork, namely between fingerlike pushers that extend into the ball guide and are provided on a swivel arm, which is rotatably mounted on the clockwork on the same axis as the clockwork axis and the rotary motion of which is converted via a gear unit into a motion for winding the driving spring of the clockwork.
The disadvantage of this is that the ball guide for the balls forming the eccentric mass extends over an angle area of 360°, so that the space required for the ball guide results in a relatively high overall height and/or a relatively large diameter for the watch case.
It is an object of the invention is to present a mechanical automatic winding device for wristwatches (automatic winding watches) that eliminates the aforementioned disadvantages while featuring a high degree of operational reliability and enables a reduced size of the watch or the watch case.